Creating paper pinwheel from an image
You may try to use Curve and Array modifiers starting with a simple plane instead of triangle.


Add a curve and a plane. Make sure they both have the origin points placed in the same position. Subdivide the plane many times with W-->Subdivide then give it a Curve modifier. Fit the plane to the curve.


Select diagonal vertices and connect them with J. Delete half vertices of the plane. One segment is ready!


Apply the Curve modifier and delete the curve. Snap the plane's origin point to the straight angled corner of a mesh as pictured below (Shift+Ctrl+Alt+C). Next add an Empty there.


Apply the transformations of the objects (Ctrl+A-->Rot&amp;Scale). Add an Array modifier to the plane, change the count number as you like, uncheck the Relative Offset checkbox and check the Object Offset one. Type Empty in the window below. Select an Empty and rotate it as you like.